OpenLB – Open Source Lattice Boltzmann Code › Forums › on OpenLB › General Topics › Mass inlet for free surface flow › Reply To: Mass inlet for free surface flow July 1, 2022 at 2:41 pm #6686 mathiasKeymaster The pressure bundary condition fixes the pressure, which is up to a constant the density. You can use that boundary condition actually by assigning the density in lattice units actually!